Feed cassette and image forming apparatus including the same

ABSTRACT

A feed cassette including a frame, a knock-up plate hinge-coupled to the frame at a first end of the plate, to tilt about the first end according to an amount of paper stacked thereon, an overlap supply preventing part provided in front of a second end of the knock-up plate, the second end being opposite the first end, and to have a frictional surface forming a predetermined intermediate angle with respect to the knock-up plate and to prevent the paper supplied from the knock-up plate from being overlappingly supplied, a tilting arm having a hinge part provided on the frame, and a main body part to support the overlap supply preventing part, to have a leaning surface contacting an edge of the knock-up plate, and to tilt about the hinge part so that the leaning surface is slidably pressurized according to a tilting of the knock-up plate such that an intermediate angle between the frictional surface of the overlap supply preventing part and the knock-up plate remains within a predetermined angle range, and an elastic supporter having both sides thereof respectively coupled to the frame and the tilting arm so as to allow the leaning surface to remain in contact with the knock-up plate during the tilting thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Application No. 2005-25015, filed Mar. 25, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a feed cassette and an image forming apparatus to which the feed cassette is attached, and, more particularly, to a feed cassette and an image forming apparatus to which the feed cassette is attached having an overlap supply preventing part that cooperates with a knock-up plate.

2. Description of the Related Art

A conventional feed cassette 10 attached to an image forming apparatus such as a printer, a fax, or a multi-function printer has a frame 11, a knock-up plate 13 to tilt about a hinge shaft 12 that is coupled to the frame 11, a overlap supply preventing part 14 provided in front of a paper supply side of the knock-up plate 13, as shown in FIG. 1. The knock-up plate 13 is supported by a spring 15, and tilts according to an amount of paper that is stacked on a top surface of the knock-up plate 13.

A paper supply roller 20 is mounted in front of the paper supply side of the knock-up plate 13 and is supported by a main body (not shown) of the image forming apparatus. The paper supply roller 20 picks up an uppermost piece of paper 1 from among the pieces of paper that are stacked on the knock-up plate 13 by the application of a rotational friction force to the uppermost paper 1 and then supplies the uppermost paper 1 to an image forming part (not shown) through the overlap supply preventing part 14. The overlap supply preventing part 14 is fixed at the frame 11 in such a way that the overlap supply preventing part 14 makes a predetermined angle with respect to the knock-up plate 13. Also, as shown in FIG. 2, a frictional pad 16 having a large friction coefficient is attached to a surface of the overlap supply preventing part 14 to form a frictional surface. In a case in which a plurality of the papers 1 and 2 are simultaneously supplied from the knock-up plate 13, the lower paper 2 is stopped by the friction force applied by the frictional pad 16. As a result, only the upper paper 1 is supplied to the image forming part.

As shown in FIG. 1, the knock-up plate 13 of the conventional feed cassette 10 tilts about the hinge shaft 12 according to the loaded paper amount. As a result, a rotational position of the knock-up plate 13, with reference to the frame 11, is changeable. Meanwhile, the overlap supply preventing part 14 is constantly fixed at the frame 11. Therefore, the larger the loaded paper amount is, the bigger an intermediate angle (θ) between the knock-up plate 13 and the overlap supply preventing part 14 is.

Thus, in a case in which the intermediate angle (θ) between the knock-up plate 13 and the overlap supply preventing part 14 is large, such as that which is illustrated in FIG. 3, a phenomenon of an edge folding 3 is generated in the paper supplied to the friction pad 16. Further, where the intermediate angle (θ) is larger, the paper stacked on knock-up plate 13 is blocked by the overlap supply preventing part 14 and may not be supplied properly.

Meanwhile, to solve this problem, if the original angle of the frictional surface of the frictional pad 16 is set at a lower position, the operation of the overlap supply preventing part 14 is not normally accomplished.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a feed cassette and an image forming apparatus which prevent a phenomenon of an edge folding of papers in the feed cassette, effectively prevents overfeeding of paper to the image forming apparatus, and allows the paper to be smoothly supplied.

According to an aspect of the invention, there is provided a feed cassette, comprising a frame, a knock-up plate hinge-coupled to the frame at a first end of the knock-up plate, to tilt about the first end according to an amount of paper stacked thereon, an overlap supply preventing part provided in front of a second end of the knock-up plate, the second end being opposite the first end, and to have a frictional surface forming a predetermined intermediate angle with respect to the knock-up plate and to prevent the paper supplied from the knock-up plate from being overlappingly supplied, a tilting arm having a hinge part provided on the frame, and a main body part to support the overlap supply preventing part, to have a leaning surface contacting an edge of the knock-up plate, and to tilt about the hinge part so that the leaning surface is slidably pressurized according to a tilting of the knock-up plate such that an intermediate angle between the frictional surface of the overlap supply preventing part and the knock-up plate remains within a predetermined angle range, and an elastic supporter having both sides thereof respectively coupled to the frame and the tilting arm so as to allow the leaning surface to remain in contact with the knock-up plate during the tilting thereof.

The leaning surface causes the tilting arm to tilt in proportion to the tilting of the knock-up plate. The leaning surface comprises a curved surface. The leaning surface comprises a flat surface. The overlap supply preventing part and the tilting arm are integrally formed.

According to another aspect of the invention, there is provided an image forming apparatus, comprising a frame, a knock-up plate hinge-coupled to the frame at a first end of the knock-up plate, to tilt about the first end according to an amount of paper stacked thereon; a feed roller provided proximate to a second end of the knock-up plate, the second end being opposite the first end, to supply a paper from an uppermost stacking position of the knock-up plate, a tilting arm part, having a frictional surface, to contact with the supplied paper and to make a predetermined angel with the knock-up plate so as to prevent the paper from being overlappingly supplied, and to maintain an intermediate angle between the frictional surface and the knock-up plate to be within a predetermined angle range as a result of the tilting arm part being hinge-coupled to the frame and being tilted due to contact and pressure of the knock-up plate, and an elastic supporter having both sides thereof respectively coupled to the frame and the tilting arm part so as to cause the tilting arm part to remain in contact with the knock-up plate.

The tilting arm part comprises an overlap supply preventing part to which the frictional surface is attached, a hinge part hinge-coupled with the frame, and a main body to support the overlap supply preventing part and to tilt about the hinge part by the contact and pressure of the knock-up plate.

The main body part comprises a leaning surface to slidably contact the knock-up plate. The leaning surface causes the tilting arm to tilt in proportion to the tilting of the knock-up plate. The leaning surface comprises a curved surface. The leaning surface comprises a flat surface.

Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a sectional view illustrating a conventional feed cassette;

FIG. 2 is a partially enlarged view illustrating a paper supply process in the feed cassette of FIG. 1;

FIG. 3 is a partially enlarged view illustrating paper supplied by the feed cassette of FIG. 1;

FIG. 4 is a sectional view illustrating an image forming apparatus according to an embodiment of the present invention;

FIG. 5 is a perspective view illustrating a feed cassette according to the embodiment of the present invention;

FIG. 6 is a sectional view of the feed cassette of FIG. 5; and

FIGS. 7A and 7B are a sectional view illustrating an operation of the feed cassette of FIG. 5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

Referring to FIG. 4, an image forming apparatus according to an embodiment of the present invention is a laser beam printer 100 although it is understood that the present invention could be applied to various image forming apparatuses. The laser beam printer 100 comprises a printer main body 101 and a feed cassette 120 mounted at a lower part thereof to supply paper.

The printer main body 101 comprises a printer cartridge 102 detachably mounted to the printer main body 101; a scanning unit 104 to form a latent image on an OPC (opto photo-organic conductor) drum 103 of the printer cartridge 102; a transfer roller 106 to engage and rotate with the OPC drum 103 so as to cause paper 5 to be transferred between the transfer roller 106 and the OPC drum 103; a fixing roller 107 to fix a toner transferred on the paper 5; a plurality of carry rollers 108 and 113; a feed roller 109 to pick up the paper 5 stacked on the feed cassette 120; and a housing 110 to support the features discussed above.

Further, the printer main body 101 comprises a driving part (not shown) to drive the features discussed above, a controller (not shown) to control the driving part, and a display part (not shown) to display an operating state of the printer. If a print order is inputted, the paper 4 stacked on a knock-up plate 121 of the feed cassette 120 is picked up by the feed roller 109 and supplied to a register roller 111 through the carry roller 108, and then passes between the OPC drum 103 and the transfer roller 106. The latent image is formed on a surface of the OPC drum 103 by the light emitted from the scanning unit 104, and the toner supplied from a developing roller 112 is transferred onto the paper 5 by electric power of the transfer roller 106. The toner transferred onto the paper 5 is heated and pressurized on the paper 5 in the process that the paper 5 passes through the fix roller 107, and then the paper 5 is discharged to the outside through the carry roller 113 and a discharge roller 114.

Meanwhile, in the operation of stacking the paper 4 on the knock-up plate 121 of the feed cassette 120 such that the paper 4 may be picked up and supplied by the feed roller 109 to the printer main body 101, the overlap supply preventing part 122 insures that pieces of the paper 4 are supplied in a one by one sequence.

FIGS. 5 and 6 are, respectively, a perspective view and a sectional view illustrating the feed cassette 120 according to the embodiment of the present invention. As shown therein, the feed cassette 120 comprises a frame 123, the knock-up plate 121 to tilt about a hinge shaft 124 coupled to the frame 123, the overlap supply preventing part 122 provided in front of a feed side of the knock-up plate 121, and a tilting arm 125 to support the overlap supply preventing part 122 and to be contacted and pressured by the knock-up plate 121 to rotate.

The knock-up plate 121 is supported by a spring 126, and tilts according to an amount of the paper stacked on an upper surface thereof. A feed roller 109 of the printer main body (refer to reference numeral 101 of FIG. 4) is provided proximate to the upper surface of the feed side of the knock-up plate 121 to pick up the uppermost paper among the paper stacked on the knock-up plate 121 and to supply the picked up paper to the carry roller (refer to 108 of FIG. 8) through the overlap supply preventing part 122.

An upper surface of the overlap supply preventing part 122 is fixed and supported to an upper end of the tilting arm 125 and makes a predetermined angle (θ) with respect to the knock-up plate 121, and a frictional pad 127 having a large coefficient of friction is attached to the surface thereof so as to form a frictional surface. In a case in which the plurality of papers are simultaneously supplied from the knock-up plate 121 to the friction pad 127, the lowermost paper of the plurality of papers is contacted and stopped by the friction surface. Similarly, the next lowermost paper is contacted and stopped in subsequent paper feeding operations. As a result, only the uppermost paper thereof is supplied.

The tilting arm 125 comprises a hinge part 128 provided on the frame 123, and a main body part 129 to fix and support the overlap supply preventing part 122 and to have a leaning surface S contacting with an edge of the knock-up plate 121. In a case in which the knock-up plate 121 tilts downwardly, that is, the knock-up plate 121 tilts about the hinge shaft 124 in a clockwise rotation, the hinge part 128 is provided in a position such that that the main body part 129 tilts in the clockwise rotation along with the knock-up plate 121. The main body part 129, wherein an upper end thereof fixes and supports the overlap supply preventing part 122 and a side of a lower end thereof is formed with an extending part 130, is elastically supported on the frame 123 by the spring 131. The tilting arm 125 is constantly contacted to the knock-up plate 121 by elastic force of the spring 131. According an embodiment of the invention, the overlap supply preventing part 122 may be formed integrally with the tilting arm 125.

The leaning surface S of the main body 129 is formed as a curved surface to face the knock-up plate 121. Therefore, in a case in which the knock-up plate 121 tilts downwardly, that is, in the clockwise rotation, the knock-up plate 121 contacts with the leaning surface (S) and pushes up the main body part 129. As a result the main body part 129 is pressured in a state of contacting with the knock-up plate 121 and tilts in the clockwise rotation. Meanwhile, in a case in which the knock-up plate 121 tilts upwardly, that is, in the counter clockwise rotation, the main body part 129 also tilts in the counter clockwise rotational direction. This is due to the fact that the leaning surface S of the main body part 129 contacts the knock-up plate 121 by the elastic power of the spring 131 during the counter clockwise rotation of the knock-up plate 121.

FIGS. 7A and 7B illustrate a positional relationship of the knock-up plate 121 and the tilting arm 125. Referring to FIG. 7A, in a case in which the papers 1 stacked on the knock-up plate 121 is stacked in small amounts, the knock-up plate 121 contacts the upper end of the leaning surface S of the tilting arm 125 in a state of tilting upwardly in the counter clockwise rotation. The intermediate angle (θ₁) between the knock-up plate 121 and the overlap supply preventing part 122 has a predetermined set value so as to insure a proper pick-up of paper by the feed roller 109 and so as to insure that the overlap supply prevention part 14 properly prevents a supply of overlapping papers.

Meanwhile, referring to FIG. 7 b, in a case in which the papers 8 that are stacked on the knock-up plate 121 are stacked in large amounts, the knock-up plate 121 tilts downwardly in the clockwise rotation and slides downwardly along the leaning surface S and pressurizes the leaning surfaces. Accordingly, the tilting arm 125 tilts about the hinge part 128 in the clockwise rotation. Therefore, the overlap supply preventing part 122, being fixed and supported on the upper side of the tilting arm 125, also tilts in the clockwise rotation together with the tilting arm 125. The tilting of the tilting arm 125 increases in proportion to an increase in tiling of the knock-up plate 121. Therefore, the overlap supply preventing part 122 and the knock-up plate 121 tilt in a similar direction, so that the intermediate angle (θ₂) between the knock-up plate 121 and the friction pad 127 of the overlap supply preventing part 122 is similar to the intermediate angle (θ₁). Accordingly, the paper 8 picked up by the feed roller 109 is not blocked and is smoothly supplied, and the phenomenon of edge folding due to a contacting of the edge of the picked-up paper with the frictional surface of the frictional pad 127 is not generated. That is, variation of the intermediate angle |θ₂-θ₁| corresponding to tilting of the knock-up plate 121 should be within a range that blocking of the paper and edge folding are not generated.

According to a test, the intermediate angle (θ₂) has resulted in similarity to the intermediate angle (θ₁) when the tilt angle of the friction pad 127 of the overlap supply preventing part 122 is between 10 degrees and 15 degrees. Such a tilt angle may be applied to the paper amounts within a range stackable on the knock-up plate 121. Further, the curved surface of the leaning surface S may be formed so that the tilt angle of the friction surface of the friction pad 127 is within the foregoing range. Alternatively, the leaning surface S is not limited as the curved surface, and may also be formed with a plane in case where the friction surface has the tilt angle within the foregoing range.

Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A feed cassette, comprising: a frame; a knock-up plate hinge-coupled to the frame at a first end of the knock-up plate, to tilt about the first end according to an amount of paper stacked thereon; an overlap supply preventing part, provided in front of a second end of the knock-up plate, the second end being opposite the first end, having a frictional surface forming a predetermined intermediate angle with respect to the knock-up plate to prevent the paper supplied from the knock-up plate from being overlappingly supplied; a tilting arm having a hinge part provided on the frame, and a main body part to support the overlap supply preventing part, to have a leaning surface contacting an edge of the knock-up plate, and to tilt about the hinge part so that the leaning surface is slidably pressurized according to a tilting of the knock-up plate such that an intermediate angle between the frictional surface of the overlap supply preventing part and the knock-up plate remains within a predetermined angle range; and an elastic supporter having both sides thereof respectively coupled to the frame and the tilting arm so as to allow the leaning surface to remain in contact with the knock-up plate during the tilting thereof.
 2. The feed cassette of claim 1, wherein the pressurization of the leaning surface causes the tilting arm to tilt in proportion to the tilting of the knock-up plate.
 3. The feed cassette of claim 2, wherein the leaning surface comprises a curved surface.
 4. The feed cassette of claim 2, wherein the leaning surface comprises a flat surface.
 5. The feed cassette of claim 1, wherein the overlap supply preventing part and the tilting arm are integrally formed with each other.
 6. An image forming apparatus, comprising: a frame; a knock-up plate hinge-coupled to the frame at a first end of the knock-up plate, to tilt about the first end according to an amount of paper stacked thereon; a feed roller provided proximate to a second end of the knock-up plate, the second end being opposite the first end, to supply a paper from an uppermost stacking position of the knock-up plate; a tilting arm part, having a frictional surface, to contact with the supplied paper and to make a predetermined angel with the knock-up plate so as to prevent the paper from being overlappingly supplied, and to maintain an intermediate angle between the frictional surface and the knock-up plate to be within a predetermined angle range as a result of the tilting arm part being hinge-coupled to the frame and being tilted due to contact and pressure of the knock-up plate; and an elastic supporter having both sides thereof respectively coupled to the frame and the tilting arm part so as to cause the tilting arm part to remain in contact with the knock-up plate.
 7. The image forming apparatus of claim 6, wherein the tilting arm part comprises: an overlap supply preventing part to which the frictional surface is attached; a hinge part hinge-coupled with the frame; and a main body to support the overlap supply preventing part and to tilt about the hinge part by the contact and pressure of the knock-up plate.
 8. The image forming apparatus of claim 7, wherein the main body part comprises a leaning surface to slidably contact the knock-up plate.
 9. The image forming apparatus of claim 8, wherein the leaning surface makes the tilting arm tilt in proportion to the tilting of the knock-up plate.
 10. The image forming apparatus of claim 9, wherein the leaning surface comprises a curved surface.
 11. The image forming apparatus of claim 10, wherein the leaning surface comprises a flat surface.
 12. A feed cassette, including a frame and a plate hinge-coupled to the frame at a first end of the plate to tilt about the first end according to an amount of paper stacked thereon, the cassette comprising: an overlap preventing part including a frictional surface at a predetermined angle with respect to the plate provided in front of a second end of the plate, the second end being opposite the first end, so as to prevent the paper supplied from the plate from being overlappingly supplied from the cassette; a tilting arm, including a leaning surface, elastically and hingeably provided on the frame to support the overlap preventing part and to contact an edge of the plate, the leaning surface being pressurized according to the tilting of the plate due to the contact between the leaning surface and the plate such that an angle between the frictional surface and the plate is within a predetermined range.
 13. An image forming apparatus having the feed cassette according to claim 12 attached thereto, the cassette including a frame and a plate hinge-coupled to the frame at a first end of the plate to tilt about the first end according to an amount of paper stacked thereon.
 14. A feed cassette, including a frame to be attachable to an image forming apparatus, the cassette comprising: a plate to rotate about an attachment of the plate and the frame in accordance with an amount of paper stacked thereon, the apparatus sequentially drawing pieces of the paper thereinto; a tilting system, including a body biased to remain in contact with the plate during the rotation thereof and a hinge to connect the body with the frame about which the body rotates as the plate rotates; and a means for preventing a drawing of overlapping pieces of paper into the apparatus within a range of angles relative to the plate supported by the tilting system.
 15. The cassette according to claim 14, wherein the image forming apparatus is a laser printer.
 16. The cassette according to claim 15, wherein the laser printer comprises: a printer cartridge; a scanning unit to form a latent image on an OPC (opto photo-organic conductor) drum of the printer cartridge; a transfer roller to engage and rotate with the OPC drum so as to cause the paper to be transferred between the transfer roller and the OPC drum; a fixing roller to fix a toner transferred on the paper; and a feed roller to pick up the paper stacked on the plate.
 17. The cassette according to claim 14, further comprising a spring to bias the plate in a direction opposite to the direction of rotation due to the amount of paper stacked therein.
 18. The cassette according to claim 14, wherein the means for preventing a drawing of overlapping pieces of paper into the apparatus comprises an overlap preventing part having a frictional surface attached thereto.
 19. The cassette according to claim 14, wherein the body of the tilting system comprises a curved surface.
 20. The cassette according to claim 14, further comprising an elastic member to bias the body toward the plate.
 21. A method of preventing edge folding of paper fed to an image forming apparatus comprising automatically tilting an overlap preventing part of a feed cassette attached to the image forming apparatus in accordance with an amount of rotation of a plate on which paper to be fed to the apparatus is stacked. 